Sounds like a fun task, and regular expressions will be your friend here... but from the example you listed, I'm not sure if the rules are totally clear to me? Could you come up with a list of criteria for "what makes a word close enough to another word"? Then we can give some more concrete ideas :)

I'm a peripheral visionary... I can see into the future, but just way off to the side.

I'll try an explain how the game works.
You are presented with a word, for example 'perlmonksisgreat'.
You have to try and make words from this using only the letters that are in the word, you can only use each letter as many times as it appears. In the above example you could use 1 x 'p' and 2 x 'e' and so on.
Some examples of valid words are 'perl', 'slop', 'term'.
An example of a non-valid word would be 'pepper' (only 1 'p').